Evaluation of a new interrupter device for measuring bronchial

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Although less sensitive when compared to air- way resistance (Raw) measured plethysmographically, or total lung resistance using an oesophageal balloon [17] ...
Copyright ERS Journals Ltd 1996 European Respiratory Journal ISSN 0903 - 1936

Eur Respir J, 1996, 9, 1374–1380 DOI: 10.1183/09031936.96.09071374 Printed in UK - all rights reserved

Evaluation of a new interrupter device for measuring bronchial responsiveness and the response to bronchodilator in 3 year old children S.B. Phagoo, N.M. Wilson, M. Silverman Evaluation of a new interrupter device for measuring bronchial responsiveness and the response to bronchodilator in 3 year old children. S.B. Phagoo, N.M. Wilson, M. Silverman. ©ERS Journals Ltd 1996. ABSTRACT: The interrupter technique for measuring airway resistance is noninvasive and convenient, and therefore ideally suited for the assessment of induced changes in airway calibre in preschool children. The aim of this study was to evaluate a commercially available interrupter device (based on Microlab 4000), which calculates the interrupter resistance (Rint) from pressure and flow following a brief interruption of expiration during quiet breathing. The repeatability of Rint was assessed, and its response to methacholine challenge and the bronchodilator salbutamol were compared with an indirect technique, the fall in transcutaneous oxygen tension (Ptc,O2), using the sensitivity index (SI, i.e. the change after challenge expressed in multiples of the baseline standard deviation) in 12 wheezy children (aged 3 yrs±2 months). The mean (SD) baseline value of Rint was 0.91 (0.20) kPa·L-1·s. Short-term repeatability and baseline variability were satisfactory for Rint (intraclass correlation coefficient = 0.6; mean intrasubject coefficient of variation = 13%). Although 10 of the 12 subjects obtained a significant response using Rint at maximal bronchoconstriction (i.e. SI >2), overall, Rint was five times less sensitive than Ptc,O2 (geometric mean SI: Rint 3 vs Ptc,O2 16; p

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